1. Field of the Invention
The present general inventive concept relates to an apparatus and method of writing/reproducing data to/from an optical disc, and, more particularly, to an apparatus and method of writing/reproducing data to/from an optical disc, which are capable of preventing an error from occurring at the time of examination of a writing strategy and searching for an optimum writing condition in a short period of time, by examining the writing strategy after adjusting a focus in a test region, in order to set a writing condition at the time of writing data.
2. Description of the Related Art
Generally, optical discs have a variety of formats and various speeds. Despite of the same format and speed, the characteristics of the disc vary according to disc makers. In order to stably write/reproduce data to/from various discs, the following method is performed.
First, a method of recognizing a disc maker or the like from disc information and writing/reproducing data to/from a disc under a writing condition prepared in firmware which is previously stored in a CPU is performed. Second, in an unknown disc which is previously stored in a writing condition table, a method of searching for a writing condition by examination of a writing strategy and writing/reproducing data to/from a disc is performed.
The conventional method of operation of an apparatus to write/reproduce data to/from an optical disc will be described below while referring to FIG. 1.
First, MID information, which is information on a disc maker, is recognized from disc information (operation S1). Next, if the recognized MID information is identical to MID information registered in the CPU (operation S2), a write pulse is generated by a writing strategy which is previously registered (operation S3), optimum power is searched for by an optimum power calibration (OPC) (operation S13), and then data is written to the disc (operation S14).
However, if the disc information (MID information) is not identical to the disc information which is previously prepared, it is determined that write pulse information of the disc is not present (operation S4), and an optimum writing strategy is searched for. Here, a method of searching for the optimum writing strategy is described below.
First, if it is determined that the write pulse information of the disc is not present (operation S4), a write pulse is generated by a general writing strategy of the disc (operation S5), and a pre-OPC is performed in order to examine the writing strategy (operation S6).
Here, the OPC searches for power having a predetermined value due to an unbalance degree, a modulation degree, and an error rate, in a reproduction signal of a writing portion having variable power.
Thereafter, a writing strategy is variably written with optimum power searched by the pre-OPC (operation S7) and a writing strategy having a minimum average jitter obtained from the reproduction signal is searched for (operation S9). Here, variable searching of a 3Ttop pulse is performed. If the writing strategy is variable, a target unbalance degree varies. Accordingly, whenever the writing strategy varies (operation S7), the pre-OPC should be performed (operation S8).
Finally, a byte error rate (BER) obtained by performing a writing/reproducing operation by the writing strategy having the minimum average jitter is checked (operation S10) and it is determined whether the writing is possible by the searched result. If the writing is possible (operation S11), a focus is adjusted (operation S12), the OPC is performed (operation S13), and the writing operation is performed (operation S14).
If the power exceeds a predetermined reference value by the pre-OPC, the occurrence of a writing error, the checking of the BER and the measurement of the jitter, if an error occurs, or if an algorithm is not normally finished, the writing operation cannot be performed due to a writing condition searching error of the disc.
However, since the adjustment of the focus of an unknown disc is performed in the jitter at the time of the writing/reproducing operation using the writing strategy after searching for the writing strategy, the writing strategy searching error occurs due to dependency on an initial focus position, and thus the writing operation cannot be performed with respect to the disc.
If the pre-OPC of the unknown disc is performed using the general writing strategy, the pre-OPC result is set to high power, which exceeds an upper limit of laser power, and thus the writing operation cannot be performed with respect to the disc.
Since the measurement of the jitter is restricted to the average jitter, only a portion (3Ttop or the like) of the write pulse which can be observed by a jitter measuring device can be searched for. Accordingly, since the searching of the writing strategy is restricted, the BER is not normally checked due to deterioration in writing characteristics (jitter loss), and thus the writing operation cannot be performed with respect to the disc.